The present invention relates generally to electrochemical cells. More particularly, the present invention provides methods and devices having a functionally graded and an architectured component for electrode(s). Merely by way of example, the invention can be applied to a variety of applications including automotive, telecommunication, general energy storage, portable electronics, power tools, power supplies, among others.
As noted, electrochemical cells are used to store energy for a variety of applications. These applications include portable electronics such as cell phones, personal digital assistants, music players, video cameras, and the like. Applications also include power tools, power supplies for military use (e.g., communications, lighting, imaging and the like), power supplies for aerospace applications (e.g., power for satellites), and power supplies for vehicle applications (e.g., hybrid electric vehicles, plug-in hybrid electric vehicles, and fully electric vehicles), and others.
Conventional electrochemical cells are manufactured using paper-making techniques. The conventional electrochemical cells have been fabricated without accounting for internal mechanical stresses, intercalation and thermal induced stresses. Thus, drawbacks exist with these conventional cells. The drawbacks include limited lifetime, premature failure, limited storage capability, and other imperfections. To increase the electrochemical cell energy and power density, without compromising lifetime, other manufacturing approaches have been proposed. Concurrently, electrode architectures have been developed that use thin-film, microarchitectured, functionally graded materials such as Li2MnO3-stabilized LiMO2 (M=Mn, Ni, Co) described in “M. M. Thackeray, S. H. Kang, C. S. Johnson, Li2MnO3-stabilized LiMO2 (M=Mn, Ni, Co) Electrodes for Lithium-Ion Batteries, Journal of Material Chemistry 17, 3112-3125, 2007”. This type of cells typically has non-aqueous electrolyte sandwiched between a cathode layer and an anode layer of similar geometry. For example, in a typical thin-film lithium ion cell, the cathode is often, LiCoO2, LiMn2O4, while the electrolyte is often lithium-phosphorous-oxynitride (LIPON) and anode is lithium foil. Thin-film Li-ion cells have been demonstrated to have energy densities of 1,000 Wh/Kg and power densities of 10,000 W/Kg with potentially unlimited number of discharge-charge cycles.
A central challenge to create cost-effectively microarchitectured and functionally graded electrodes, cells or batteries is precisely tuning material properties for the specific role of that material needed. In order to achieve precise material properties spanning through an electrochemical cell manufacturing has to be inside a controlled environment. Traditional thin-film electrochemical cells have been manufactured inside the clean room for aerospace and implantable batteries. However, such a process is too costly and can not be used for mass production of high-tech electrochemical cells.
As a consequence, cost-effective high throughput manufacturing techniques and microarchitectured and functionally graded electrodes are desirable.